1. Related Applications
This application claims the benefit of priority under 35 U.S.C. § 119 to Japanese patent application no. 2006-148924, filed May 29, 2006, the disclosure of which is herein incorporated by reference in its entirety.
2. Field of the Invention
The present invention relates to a charged-particle beam apparatus for inspection and monitor in the field of semiconductor device production, and particularly to a stage and an X-Y stage each on which to place a sample, and which are used for the charged-particle beam apparatus.
3. Description of the Related Art
Many of stages for measuring objects in charged-particle beam apparatuses for inspection and monitor in the field of semiconductor device production, particularly in scanning electron microscopes for inspection of semiconductor wafers are X-Y stages each having a motor as a drive source, and each configured by stacking up tables which move in their own uniaxial directions. Each of such stages is positioned in the order of microns at a high speed. For this reason, the stage needs high-precision ball screws and a no-lost-motion mechanism with which the ball screws and corresponding tables are tightly locked with each other in order that the ball screws can be free of play.
In a case where this type of no-lost-motion mechanism is employed for a stage, an image drift of a measuring object is observed when the measuring object is monitored by use of an electron microscope. This is because a ball screw which has expanded due to heat of dynamic friction generated in the ball screw while a corresponding table is moving undergoes heat shrinkage once the table stops, and accordingly moves the table again.
What is termed as a servo drive control has been proposed for the purpose of avoiding a table being moved due to heat shrinkage. The servo drive control is that for monitoring the position of a stage in real time, and thus feeding back the position to the number of revolutions of a motor to which a ball screw is connected, or the amount of deflection of an electron beam to be irradiated on the table, in accordance with heat shrinkage of the table. In addition, a gap junction control has been proposed. The gap junction control is that for positioning a table with a gap of 20 μm to 100 μm given to a junction between a ball screw and a table, thereafter mechanically separating the junction between the table and the ball screw by use of the gap, and thereby avoiding the table being again moved due to heat shrinkage. (see Japanese Patent Application Laid-open Publication No. 2004-134155, for example)